Numbers Count: Personal Examples When Counts Mattered - Central Valley Bird Club

Numbers Count: Personal Examples When Counts
Mattered

John Fulton, 927 Olivewood Drive, Los Banos, CA 93635.
         Merced_birding@hotmail.com

     Certain times in our lives are formative. The following anecdotes describe
situations when numbers mattered to me. Although these events did not
happen in the Central Valley, the processes involved are universal in the sense
that they can be applied anywhere.
OVER 700,000 WARBLERS PASS OVER QUEBEC IN A DAY
     On 28 May 2018, Grandmont et al. (2018) observed a huge wave of
migrating birds at Tadoussac, on the St Lawrence River in Quebec, Canada.
Davies reported the event on eBird that day, stating, “Today was the greatest
birding day of my life.” He reported that over their nine hours of observation,
“Total number of warblers: 721,620. To our knowledge, the previous warbler
high for a single day in the region was around 200,000, which was the highest
tally anywhere in the world. Other observers in the area today had multiple
hundreds of thousands, so there were likely more than a million warblers
moving through the region on 28 May 2018. There’s no place like Tadoussac.”
     Once posted on eBird, the report was forwarded and announced on
multiple California birding list-serves over the ensuing week. Luckily,
somebody was there in Quebec to see this amazing event. More importantly,
the numbers and the methodology to derive those numbers was also well-
documented. The post included how the seven observers took timed
observations repeatedly to calculate how many birds of each species per
second were moving through each flight path or field of view. These were
tabulated and then multiplied by the duration of each of 20 timed intervals to
arrive at the grand total. See the Quebec 28 May 2018 web posting
(Grandmont et al. 2018) for more, including photos, videos, maps and the
numbers of each species.
     The extrapolation that over a million birds may have arrived in that wave
was plausible only because the methodology was explained. Absent such an
explanation, the report could be questioned, or ignored as hyperbole, or even
deleted by an eBird editor and the data lost to future generations of
interested birders and scientists.

38                                            Central Valley Birds, Spring 2019

GULF SPRING MIGRANT FALLOUTS
     When northward migrating birds depart from the Yucatan peninsula on
their trans-Gulf migration flight, it is usually sunset. They reach land again 10
to 20 hours later, depending upon weather and wind conditions.
    My years living in the southeastern U.S. in the 1980s gave me several
chances to see incredible concentrations of migrating birds. I had many
opportunities to count large flocks of migrants: 1,500 accipiters, 1,000
American Robins (Turdus migratorius), 400 Indigo Buntings (Passerina
cyanea), 200,000 ducks, and 1,000 Broad-winged Hawks (Buteo platypterus).
Some of the winter roosts were impressive too: 1,200 Double-crested
Cormorants (Phalacrocorax auritus), 400 Turkey Vultures (Cathartes aura),
and 1.2 million blackbirds spent the winter near Mobile Bay.
      I also heard many old-timers’ stories from the 19th and early 20th Century
about “fallouts”—huge waves of migrating spring warblers and other species
along the US Gulf Coast—when there would have been hundreds of warblers
resting from exhaustion on the beach at the edge of the surf, and hundreds
more in the beach grass on the nearby dunes. The exhausted warblers land on
the sandy shores of the Gulf of Mexico to rest a minute or two, after fighting
squalls of bad weather during the long flight from the Yucatan Peninsula. The
historical reports from the early 20th century stated that some birds would be
too tired to fly any more, even to attempt escape when a person picked them
up. I had doubts about waves of hundreds of birds. Judith Toups and Jerome
Jackson (1987) mention these fallouts decades later, as warblers would arrive
on the coast in waves, but with numbers in the dozens rather than hundreds,
with as many as 20 species in mixed flocks. Despite diminished numbers, it is
still impressive, especially when you think about the birds scattered the full
length of the Gulf of Mexico.
     In the 1980s, I counted “only” up to 20 birds per 100 meters that had
landed upon the beach during a spring fallout event at Gulf Shores, Alabama.
While warblers predominated, there were thrushes, tanagers, and vireos in
the mix. Due to this relative paucity of birds in my limited experience on the
Gulf Coast compared to 50 or 100 years earlier, I wondered if the historical
reports had been exaggerations or if populations of birds had declined by at
least an order of magnitude. The 28 May 2018 eBird account from Quebec of
700,000 migrants, with supporting count methodology, substantiates the
magnitude of numbers reported in those recent historic records. It also makes
us wistfully aware of the decline that avian populations have experienced in
the past century.

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NUISANCE BIRD ROOST ASSESSMENT
     While working for the US Department of the Interior in northern Georgia
in late fall 1982, my supervisor dispatched me to respond to a hazardous
animal call. A person complained that millions of blackbirds were causing a
serious health concern near Gainesville, Georgia. I found the flock roosting in
a bamboo thicket and counted the bird numbers present. As the birds swirled
overhead in the light of the setting sun, I used progressive visualizations
(Fulton and Kajrys 2019) to get my best estimate of the numbers. The swirling
flight did make it a bit more challenging. They were not blackbirds, and there
were not millions of them. The roost supported

and distance of the microphone detection cone; he quantified the numbers
and the density of the birds flying at different heights. Bill identified the calls
of the different thrush species and then established a minimum number for
each species. He quantified the ratios and minimum magnitudes of the
migration waves (Evans 2005). Without careful and detailed quantitative
methods, all he would have learned was that some thrushes migrate at night.
    In presenting his data, Bill described his equipment and his techniques.
He carefully described his count methods so other researchers could interpret
the data. He explained his data analysis process and admitted the limitations
of his methods. Careful description of count methods and results allowed
others to use the same methods to try to replicate the results and collect
comparable data elsewhere.
ROOST COUNTING
     While working on National Wildlife Refuges, my duties included
documenting the numbers of birds using the refuge each month. We did
separate monthly counts for various bird groups. Our counts focused on
waterfowl, raptors, shorebirds, colonial waders and endangered species. Each
group was broken down into species-specific tallies. Newly established
refuges needed to have procedures established so that these counts could be
used to track population trends and habitat use over time. Counting birds in
daylight and apportioning the numbers to several species can be done in
more than one way. Roost counts may be one of the easiest. It is relatively
easy to count wading birds coming into a roost. Experienced observers can
distinguish distant silhouettes of each species of white wader: Cattle Egret
(Bubulcus ibis), Great Egret (Ardea alba), Snowy Egret (Egretta thula), White
Ibis (Eudocimus albus), immature Little Blue Heron (Egretta caerulea), white
morphs of Great Blue Heron (Ardea herodias) Reddish Egret (Egretta
rufescens), and Wood Stork (Mycteria americana). It is trickier with a flock of
mixed blackbirds, grackles, starlings, and cowbirds because they are smaller
and usually are in greater numbers and at greater distances than waders.
     When counting several thousand ducks on a pond, I would visually
discriminate the identity of the species that are closest, in order to get
percentages of each, and then multiply the percentages by the total number
of birds to derive total numbers for each species. (This method is well-
explained by Grandmont et al. [2018] who used the technique to determine
the numbers of warblers of each species in a mixed flock.) Alternatively, I
would identify duck species by flight behavior or silhouette as they took to
the air if disturbed. Disturbance may flush ducks that were unidentifiable
before because they were too distant or partially hidden in vegetation. Ducks
are easier to identify to species than mixed blackbirds or mixed white waders.
Counting the total number is very similar. I would use a grid to calculate the

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area and multiply that by the density for a stationary flock. If the birds were
flying, I would take sample counts. Every time the flock density changed I
would record the time and take a new sample count. That way I would know
the length of time by which to multiply by the birds per unit time, to yield the
number of birds passing during each time interval for each swath of the
habitat or each flight path. For more details see Fulton and Kajrys (2019).
      Alternatively, I would tally different species individually. This can be
difficult if the distance involved makes detection or identification difficult for
those birds that are most distant. I have seen some biologists successfully use
a tally sheet and mark down bird numbers as they flew by. Doing counts
alone, I found that it was easy to mark a number in the wrong column and to
not notice. I found it easier to use an audio recorder to record counts as they
happened. Looking down at the data sheet was time that I could not observe
the birds’ flights, while the audio record could be transcribed later.
COUNTING GREEN HERONS AT A BREEDING COLONY
    I was censusing nests of Green Herons (Butorides virescens) in Mississippi
at Yazoo NWR in 1984 (White et al. 1988) when a revelation came to me. I
had previously assumed that they were solitary nesters until I surveyed a
swamp with scattered buttonbush (Cephalanthus occidentalis) surrounded by
a 100-acre green-tree reservoir. There, on one of the monthly heron counts, I
counted a dozen Green Herons among the thousands of larger herons in the
roost. I assumed that there could have been as many as six nests in close
proximity. Over the next few days, researcher Keren Ensor and I were
surprised to find that there were about two dozen nests there, and that the
adults were much less conspicuous than I had expected. We flagged and
numbered individual nests and watched them progress from egg-laying
through fledging. We documented that as the young began leaving the nests
and “branching”, the nests’ twigs were recycled by other adults to build other
nests, often within a few feet of the previous nest. Over the 10-week breeding
season, we documented over 50 successful Green Heron nests in the
reservoir, without detecting any re-use of the same nests.
     In this instance, counting individual nests during one or a few visits was
not sufficient to understand the size of the colony. Conducting a full census of
breeding efforts required marking, labeling, and counting each nest as it was
built, and then following its success through the season. Such methods have
been independently developed to quantify nesting at a Sacramento colony
(Kopp 2018). Careful counting efforts make a difference.
LESSONS LEARNED
   My experiences taught me several important lessons about counting
under complicated or difficult conditions.

42                                             Central Valley Birds, Spring 2019

Be prepared to adapt to unexpected conditions. You may need to “wing
it” and adjust “on the fly.” Encountering large flocks unexpectedly may
provide your only chance to document an unusual event. Get the best data
you can when you can.
    Bad weather can be good for birding. Rain squalls can cause migrating
warblers to become concentrated in space and time. This can result in
impressive concentrations if you are prepared to brave the elements. Being in
the right place at the right time, however, is more a result of good planning
than mere good luck.
     Old technology can be used for new applications. Bill Evans used five-
gallon paint buckets to improve the sensitivity of microphones. He used the
concept of birding by ear, to develop the new field of study that identified and
counted birds in the dark.
     Do not let generally accepted assumptions cause you to jump to
conclusions before you gather the data. The secretive lives of Green Herons
may cause some to think that they are solitary and that they may re-nest in
the same season. Our study showed Green Herons sometimes nest in sizeable
colonial rookeries and we detected no nest re-use.
   Making careful observations and taking detailed notes is the best way to
maximize our contributions to citizen science.
LITERATURE CITED
Evans, W.R. 2005. Monitoring avian night flight calls—The new century ahead.
The Passenger Pigeon 67:13-24.
Evans, W.R. 2009. Bird calls and songs. Thrush calls 1: flight calls. https://
pjdeye.blogspot.com/2009/02/thrush-calls.html.
Fulton, J. and G. Kajrys. 2019. The art of counting: How to estimate flock sizes.
Central Valley Birds 22:16-24.
Grandmont, F-X, I. Davies, S. Dzielski, T. Grandmont, T. Lenz, and T. Auer.
2018. Documenting numbers and methods. (Quebec eBird entry for 28 May
2018 on warbler migration.) https://ebird.org/view/checklist/S46116491.
Kopp, D. 2018. Colonial nesting by Green Herons in Sacramento, California.
Central Valley Bird Club Bulletin 21: 108-114.
Toups, J.A., and J.A. Jackson. 1987. Birds and Birding on the Mississippi Coast.
University Press of Mississippi, Jackson.
White, D.H., W.J. Fleming, and K.L. Ensor, 1988. Pesticide contamination and
hatching success in waterbirds In Mississippi. Journal of Wildlife Management
52:724-729.

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